1. Field
The following description relates to a temperature sensing apparatus and method and an infrared light sensing apparatus and method that may be used in a bulk acoustic wave resonator (BAWR) based on a temperature coefficient of frequency (TCF).
2. Description of Related Art
A bulk acoustic wave resonator (BAWR) refers to an acoustic device that may resonate in a predetermined frequency. A resonant frequency of the BAWR may vary depending on a temperature. Materials forming each layer of the BAWR may each have a temperature coefficient of frequency (TCF), for example a positive TCF, and a negative TCF. The TCF refers to a coefficient indicating a rate at which a resonant frequency changes due to a change in temperature.
In general, most materials forming each layer of the BAWR have negative TCF. For example, sensitivity of a BAWR including materials with a negative TCF may range from about −25 ppm/° C. to −35 ppm/° C. In other words, when each of layers of a BAWR is formed of materials with the negative TCF, temperature detection sensitivity used to detect a change in a resonant frequency due to a change in a temperature is very limited.
Accordingly, there is a desire for a temperature sensing technology that may accurately detect a change in a resonant frequency due to a change in a temperature.